Diaphragm chuck



March 15, 1949. f Q HOHWART ET AL 2,464,507

DIAPHRAGM CHUCK Filed July 15, 1946 Patented Mat'. 15, 1949 DIAPHRAGM CHUCK George Hohwart and Ernest F. Hohwart, Detroit, Mich., assignors to N. A. Woodworth Company, Ferndale, Mich., a corporation of Michigan Application July 13, 1946., Serial No. 683,457

8 Claims.

This invention relates to diaphragm chucks and particularly to a new and novel means for mounting and locking the work gripping jaws in position on the diaphragm thereof.

Objects of the invention include the provision of a diaphragm chuck including a diaphragm having a generally radially arranged jaw base secured to the face thereof, a jaw radially adjustably associated with the base, and a novel form of adjusting and backing up means `for the jaw; the provision of a construction as above described in which the jaw base is provided with a longitudinally extending groove in which a jaw member is radially adjustably received and in which a backing-up member for the jaw is also radially received and locked in radially outward relation with respect to the jaw member; the provision of a construction as above described in which the groove in the jaw base is so formed and so cooperates with the jaw member as to prevent any movement of the latter except longitudinally of the groove; the provision of a construction as above described in which the groove is of dovetailed character and the jaw is formed for complementary engagement therewith, the jaw member being so constructed and arranged as to permit it to be laterally iieXed into binding engagement with respect to the walls of the groove; the provision of a construction as above described in which the backing-up member similarly cooperates with the groove but is locked against longitudinal movement in the groove by means of a setscrew serving to bind the sides of the dovetailed rib thereon against the side walls of the groove; the provision of a construction as above described in which the backing-up inember is provided with a radially directed adjusting screw through which actual contact is established between it and the jaw; the provision of a construction as last described in which the adjusting screw in the backing-up member overlies the end of the setscrew in the backing-up member thereby to positively preclude backing oi of the set-screw and consequent loosening of the backing-up member in the jaw base; and the provision of a construction as above described in which the groove in the basev is provided with a depression in which the setscrew seats.

The above being among the objects or the present invention, the same consists in certain novel.

features of construction and combinations of parts to be hereinafter described in reference to the accompanying drawing, and then claimed, having the above and other objects in view.

In the accompanying drawing which illustrates suitable embodiments of the invention and in which like numerals refer to like parts throughout the several diierent views,

Fig. 1 is a sectional view taken longitudinally through the center of the diaphragm chuck embodying the present invention, as on the line l--l of Fig. 2;

Fig. 2 is a partially broken face View of the chuck shown in Fig. l;

Fig. 3 is an enlarged, fragmentary, transverse sectional view taken on the line l3--3 of Fig. 1 and disclosing in greater detail the interengaging parts of the back-up member and the jaw base and the cooperation between the adjusting screw for the jaw and the locking screw for the backing-up member;

Fig. 4 is an enlarged, fragmentary, transverse sectional View taken on the line 4--4 of Fig. l and illustrating the interengaging relationship between the jaws and the jaw base and the means provided for locking the jaws in adjusted position to the jaw base; and

Fig. 5 is a fragmentary sectional View taken in the same plane as in Fig. 1 but illustrating the use of the invention in a chuck for engaging a piece of work internally of a bore thereof instead of the outside diameter of a piece of work as in the case of the chuck in the preceding views.

It is desirable in diaphragm chucks that the jaws thereof be adjustable radially in order to adapt a chuck to receive workpieces of diierent diameters. However, in order for such adjustable jaw constructions to be practical, means must be provided for locking the jaws in their adjusted positions positivelyagainst inadvertent movement. This is important for the reason that diaphragm chucks are usually employed. for grinding or other machining operations on a piece of work where concentricity between the machined surface and the part must be held within very close limits, so that any shifting of the jaws would render the chuck temporarily, at least, useless and might result in the production oi scrap pieces if use is continued after shifting of a jaw. The present invention provides a novel means by which such jaws may be effectively locked in radially adjusted position.

In diaphragm chucks having adjustable jaws, it is conventional practice to mount a screw at the radially outer end of a jaw in a suitable support in which it is threaded so as to enable it, through contact with an end of the jaw, to shift the jaw radially in accurately controlled and extremely small increments of movement to permit the jaw to be accurately located in a predetermined position necessary to hold a piece of work concentric with the axis of rotation of the chuck. Such supports are conventionally secured to the forward face of the diaphragm and the engagement between the adjusting screw and the jaw in such cases serves to aid in holding the jaw against radial outward displacement under the centrifugal force to which it is subjected during continued operation. It is therefore essential to so secure the adjusting screw supporting member to the diaphragm that possibility of its inadvertent loosening and becoming thrown off of the chuck by the centrifugal force to which it is subjected during operation is precluded, as in such case such movement of the jaw itselfis also precluded. The present invention provides a novel means for positively locking such adjusting screw support-- ing member or backing member against inadvertent displacement on the chuck.

Referring now to the accompanying drawing, and particularly to Fig. 1, the diaphragm chuck there shown by way of illustration includes a disklike mounting member i8 -which is piloted upon the forward face of a flange l2 formed integrally with-thel forward end of a machine tool spindle I4, the mounting member I8 being secured to the iange i2 by means of screws I6. Piloted upon the forward face of the mounting member l is a ring I8 which, as will hereinafter be more fully brought out, constitutes a cylinder. A backing plate 28 is piloted upon the forward face of the ring I8. Screws 22 project rearwardly through the backing plate 20 and ring i8 and are threaded into the mounting plate lll to secure all of these parts together in assembled relationship. Additionally, screw, 24 projecting forwardly through the ring |'8 and threading into the backing plate 26 serve to maintain these two parts in assembled relationship for assembly purposes. A cupshaped diaphragm 26 forms the axially outer face of the chuck and its open end is received over and piloted upon the periphery of the backing plate 20 and while, in accordance with the present invention, it may be secured thereto by any suitable means, it is preferably brazed o r welded thereto. The diaphragm 26, as brought out in Fig. l, increases in thickness radially from its peripheral portion to the central portion as is common in this type of chuck.

Although forming no part of the present invention, and shown simply by way of illustration as one means for operating the diaphragm 26, a piston 28 is slidably received in the bore of the ring I 8 and its periphery is provided with conventional O-ring seal 36 engaging the bore of the ring I8 to effect a seal between the periphery of the piston and the bore of the ring I8. A sleeve 32 concentric with the axis of the chuck is axially slidably received in a central bore in the backing member 28 and abuts at its opposite ends against the forward face of the piston 28 and the rear face of the diaphragm 26, respectively, for transmitting force from the piston to the diaphragm in order to move the latter axially outwardly to spread the jaws Ato receive a piece of work therein.

To actuate the piston 28, a tube such as 34 is threaded into a central opening 36 in the mount-- ing plate I0 and may be connected to any suitable source of uid under pressure. Upon the application of pressure to the tube or pipe 34, such pressure is exerted between the rear face of the piston 28 and the forward face of the mounting plate IU and acts to spring the center of the diaphragm 26 outwardly by pressure applied through the sleeve 32. Preferably, the diaphragm 26 is oentrally cut away as at 38 to a diameter equal to the bore of the sleeve 32 so as to permit work to project axially through the diaphragm whereV necessary for proper chucking operations. In the particular case shown, the piston 28 is provided With a central opening therein which is closed by a screw member 40 secured in place by means of a nut 4,2. The screw member 40 is provided with a forwardly opening central threaded aperture 44 in which a suitable stop member such as 46, adapted to engage and limit the projection of a piece of kwork through the opening 38, may be threadably received.

The above described features form no part of the present invention, but do form at least part of the subject matter of our copending applications for Letters Patent of the United States for improvements in Diaphragm chuck, Serial No. 563,056, filed November 11, 1944, now Patent #2,403,599, and Serial No. 683,458, filed July 13, 1946.

It will be appreciated, of course, that a diaphragm chuck constructed in accordance with the present invention may -be equipped with any desired number of jaws, the chuck shown by way of illustration in the drawing being shown as equipped with four equally angularly spaced jaws simply for the purpose of illustration. To mount each jaw on the diaphragm, there is a corresponding jaw base 5U. Each jaw base 50, in the particular form shown, comprises a radially elongated and rectangularly sectioned piece of metal which is rigidly secured to the outer axial face of the diaphragm 26. While the manner of securing the jaw bases 58 to the diaphragm 26 in accordance with the present invention is immaterial, preferably and as disclosed and claimed in our copending application, Serial No. 683,456, led July 13, 1946, they are preferably welded or brazed to the diaphragm 26 so as, in effect, to be integrally united therewith thereby to positively preclude possibility of shifting or creeping under repeated flexing of the diaphragm. As best brought out in Figs. 3 and 4, each jaw base 50 is longitudinally and centrally provided in its outer face with a dovetail groove 52. Each groove 52 is provided with at least one, and preferably, as shown, a plurality of spaced depressions or pockets 54 centrally of its bottom face.

The jaws 56 are radially elongated and generally of rectangular cross-sectional configuration except that the axially inner face of each is provided with a dovetail rib 58 which, as best brought out in Fig. 4, is complementary to and is received in the dovetail groove 52 of the corresponding jaw base 50. The t between the dovetail rib 58 and the dovetail groove 52 is preferably such as to draw the axially inner faces of the jaws 56 along the base of the rib 58 into contacting engagement with respect to the axially outer face of the jaw base 50, as shown. Also as best brought out in Fig. 4, each jaw 56 is medially and longitudinally slotted as at 60 over its full length and from its axially inner face to a point adjacent to but spaced from its axially outer face, so as to render ible.

its axially inner edge more or less laterally ilex- One or more setscrews S2, shown-as two for the purpose of illustration, are threaded through one of the slotted sides of each jaw 56 intermediate the inner and outer ends of the corresponding slots 60 and their inner ends abut against the other slotted side of the jaw1 From this it willbe appreciated that when a jaw 56 is mounted yon its corresponding base 50 with its rib 58 in interfltting relation with respect to the groove 52 of such jaw base and the setscrews 62 are tightened up, the inner edge of the jaw 56 is causedto be spread and the beveled sides ofthe ribs 58 in being expanded against the beveled sides rof .the groove 52 not only serve to draw the axially inner face of the jaw 55 against the axially outer face of the jaw base llbut tend to frictionally lock all of these surfaces together and thereby lock the jaw 56 in radially adjusted position to the base 50.

Radially outwardly of each jaw 5B an adjusting 'screw support or backing-up member "lil is mounted on each jaw base 59. As best brought out'in Fig. 3, each backing-up member 15 is provided on its axially inner face with a dovetail bead or rib I2 which is substantially identical to the dovetail bead 58 of the jaws 56 and which correspondingly is arranged in intertting relationship with respect to the dovetail groove 52 of the jaw base. In this case, however, in order to secure the backing-up member to the jaw base 50, a setscrew such as M is threaded through the backing-up lmember 'Hl in parallel relation with respect to the axis of the chuck and its inner end projects into one of the depressions 54, thereby in'this case to mechanically lock the member 10 against radial movement in the groove 52. Each backing-up member 'Ill is further provided with a threaded opening 'I8 extending radially of the chuck and centrally of the width of the corresponding jaw member 56, and an adjusting screw l is threadably received in each opening 16 with its inner end abutting against the radially outer end of the corresponding jaw 56. A lock nut 80 on the outer end of each adjusting screw 18 is adapted to be jammed against the axially outer face of the corresponding backing-up member 'l5 to lock the screw 18 against inadvertent movement.

In accordance with the present invention and in order to prevent any possibility of the setscrews 'lll from becoming loosened during operation of the chuck and backing out of interlocking relationship with respect to the corresponding depression 54, the setscrews 'I4 are made of a length such that when one is fully engaged in one of the depressions 54, the axially outer'end thereof just clears the axially inner edge of the corresponding adjusting screw 18, as brought out in Fig. 3. yIt will be appreciated from this feature that as long as an adjusting screw 18 remains projected through a backing-up member 7B it is impossible for the corresponding setscrew 'i4 to back out and permit the backing-up member l@ to fly radially outwardly of the corresponding jaw base under the centrifugal force to which it is subject in operation and thus present a possibility lof the jaw itself from following such course of movement which, of course, would be extremely dangerous to the workmen operating the machine on which .the chuck is mounted. Thus, this feature positively' precludes the possibility of a backing-up member from becoming loosened and being thrown, either alone or with a jaw 56, from the chuck during operation and therefore provides .animportant safety factor in diaphragm chucks having radially adjustable jaws.

The provision of a plurality of depressions 5d in the length of a jaw base 50, each one of which is capable of receiving the inner end of a setscrew 14, permits the chuck to be adjusted to move the backing-up member 10 to any position in the length of the jaw base 55 required in ad justing the jaws 56 to take various diameters of workpieces without detracting in any extent from the :safety feature above described.

The chuck shown in Figs. l-e inclusive, is, of course, that type of chuck intended to grip an outer peripheral lsurface of a piece of work during a machiningoperation. Where .the chuck is to be adapted for internal chucking, that is where the jaws are intended to engage the Walls of a boreof a piece lof work during a machining operation, then the jawsmay be formed as illustrated in Fig. 5. The jaw structure illustrated in Fig. 5 is identical to that illustrated in the rst described construction except that the jaws themselves, here illustrated as at 56a, are provided at their radially inner ends with axially projecting tongues 84 which are adapted to project into the bore of a piece of work, as indicated. In this case, it will be appreciated that the diaphragm 25 must be flexed inwardly in order to receive or release a piece of work, yinstead of outwardly as in the preceding construction, and that the diaphragm 25 must be locked to the piston 28 so as to cause its central portion to move rearwardly with it when the p-iston is forced rearwardly. Accordingly, in this case the screw 35 is dispensed with and in its place is substituted a screw 86 whose head 88 overlies the outer face of the diaphragm 25. The screw 35 projects through the sleeve 32 and through the piston 28, and at the rear of the latter receives a nut 50. The rear end of the screw 86 is provided with alongitudinal passage 52 which connects with a cross passage 94 leading to the space between the forward face of the piston 28 and the rear face of the backing member 25. A tube or pipe 95 which slidably projects through the mounting plate lil and threads into the passage 52, is connected to a suitable source of fluid under pressure, or which may be placed under pressure. Thus, upon the application of pressure to the piston,the vpiston 28 is moved axially rearwardly and through the screw 86 serves to correspondingly withdraw the central portionA of the diaphragm 26 with it.

vAnother dilerence that may be noted in connection with the construction illustrated in Fig. 5 is that Where a piece of work such as shown is internally chucked, then an axially located stop such as 46 in the first described construction, is useless. Accordingly, in this case, a plurality of stops inthe form of pins such as 96, arranged in angularly spaced relationship about the axis of the chuck and in eccentric relation with respect thereto, are projected through the diaphragm 26 and threaded at their rear end into the backing plate 20, their forward ends being so spaced radially from the axis of rotation as to contact the rear face of the work and thereby limit its rearward movement with respect tov the chuck. As in the case of the operating mechanism first described, these last features form' no part of the presentinvention but are'shown and certain of them claimed in one or more of the previously identified applications, and are shown here merely by way of illustration of a suitable design `for a chuck of the type shown andto which the jaw mechanism of the present invention may be applied.

In both of the constructions shown, counterweights 98 are shown secured to the rear face of the diaphragm 26 in line with each jaw base 50. These counterweights are provided for offsetting the tendency of the jaws and jaw bases to open under the effects of contrifugal force and release the work therein. Such counterweights are not illustrated in Fig. for the reason that any tendency of the jaws 56a to spread under the effects of centrifugal force are additive to the effects of the diaphragm in securely gripping the work and are therefore unnecessary in such case.

Having thus described our invention, what we claim by Letters Patent is:

1.: In' a diaphragm chuck of the class including a mounting plate and a diaphragm peripherally secured thereto, the combination with said diaphragm of a jaw base xed to the axially outer face thereof, said jaw base having guide means extending radially of said chuck, a jaw received by said jaw base and guided in radially adjustable movements by said guide means, means for clamping said jaw to said jaw base in radially adjusted position thereon, a back-up member carried by said jaw base in radially outward relation with respect to said jaw thereon, means cooperating between said back-up member and said jaw including an adjusting screw, and means for locking said back-up member to said jaw base including a screw member locked against retraction by said adjusting screw.

2. In a diaphragm chuck of the class including a mounting plate and a diaphragm fixed at its periphery with respect threto, the combination with said diaphragm of a jaw base fixed to the axially outer face thereof, a jaw member mounted on said jaw base, said jaw base and said jaw member having interengaging dovetail portions extending radially of the axis of rotation of said chuck serving to guide said jaw on said jaw base during radial adjustment of the former, the dovetail portion of said jaw being slotted whereby to render the axially inner portion thereof laterally flexible in a plane perpendicular to the direction of length of said dovetail, and screw means -cooperating between the slotted sides of said jaw operable to flex said flexible inner edge of said jaw into frictional clamping engagement with said jaw base.

3. In a diaphragm chuck of the class wherein there is a mounting plate and a diaphragm peripherally fixed with respect thereto, the combination with said diaphragm of a generally radially directed jaw base xed to the axially outer face thereof, said jaw base having a dovetail groove in its axially outer face, a jaw member having a dovetail on its axially inner face received in complementary engagement in said dovetail groove, and means operative to laterally spread said dovetail in'said dovetail groove whereby to fric tionally lock said jaw member to said jaw base.

4. In a diaphragm chuck of the class wherein there is a mounting plate and a diaphragm peripherally fixed with respect thereto, the combination with said diaphragm of a generally radially directed jaw base fixed to the axially outer face thereof, said jaw base having a dovetail groove in its axially outer face, a jaw member having a dovetail on its axially inner face received in complementary engagement in said dovetail groove, said jaw member being slotted through said dovetail and over the radial length thereof from the axially inner face thereof to a point spaced from but adjacent the axially outer face thereof, and screw means threaded through one of said slotted sides and abutting the other thereof operative to spread said dovetail in said groove whereby to frictionally lock said jaw member to said jaw base.

5. In a diaphragm chuck of the class wherein there is a mounting member and a diaphragm is peripherally fixed with respect thereto, the combination with said diaphragm of a jaw base xed to the axially o uter face thereof, said jaw base having a dovetail groove in its axially outer face, a jawmember having a dovetail slidably received in said groove, a member having a dovetail slidably received in said groove, a setscrew threaded into said member in generally parallel relation with respect to the axis of said chuck and bearing against the bottom of said groove, and an adjusting screw projecting through said member in parallel relation with respect to said groove and engaging said jaw member, said adjusting screw intersecting the path of threaded movement of said setscrew in said member and lying in closely adjacent relation with respect to the axially outer end thereof whereby to provide a stop to lock said setscrew against inadvertent loosening.

6. In a diaphragm chuck of the class wherein there is a mounting member and a diaphragm is peripherally fixed with respect thereto, the combination with said diaphragm of a jaw base xed to the axially outer face thereof, said jaw base having a dovetail groove in its axially outer face, a jaw member having a dovetail slidably received in said groove, a member having a dovetail slidably received in said groove, a depression in the bottom of said groove, a setscrew threaded into said member and projecting into said depression, an adjusting screw threaded in said member in a direction parallel to the direction of adjustable movement of said jaw member in said groove and adapted to abut said jaw member, said adjusting screw intersecting the path of threaded movement of said setscrew in said member and extending into closely adjacent relationship with respect to the axially outer end of said setscrew whereby to lock said setscrew against withdrawal from said depression.

7. In a diaphragm chuck of the class wherein there is a mounting member and a diaphragm is peripherally fixed with respect thereto, the combination with said diaphragm of a jaw base fixed to the axially outer face thereof, said jaw base having a dovetail groove in its axially outer face, a jaw member having a dovetail slidably received in said groove, a member having a dovetail slidably received in said groove, said jaw base having a plurality of radially spaced depressions in the bottom of said groove, said member having a setscrew projecting therethrough in a direction perpendicular to the face of said diaphragm and adaptable for engagement with any one of said depressions and received in one thereof, an adjusting screw threaded through said member in radial relation with respect to the axis of said chuck and adapted to engage said jaw member, said adjusting screw intersecting the path of threaded movement of said setscrew in said member and extending over the axially outer end'of said setscrew in closely adjacent relation ,with respect thereto whereby to prevent the ywithdrawal of said setscrew from that one of said depressions with which it is engaged.

8. In combination with a chuck having an axially outer face, a jaw member radially adjustable on said face, said face and jaw member having interengaged dovetail portions for guiding and locating said jaw member on said face, a backing-up member having a dovetaii portion intertting said dovetail portion on said face and being locatedradially outwardly of said jaw member, a depression in the dovetail portion of said face, a setscrew threaded into said backing-up memberjand projecting into said depression, and an adjusting screw threaded in said backing-up member in intersecting relation to the path of threaded movement of said setscrew in said backing-up member and bearing against said jaw member, said adjusting screw substantially contacting that end of said setscrew opposite said depression whereby to form an abutment preventing retraction of said setscrew from said depression.

GEORGE HOHWART. ERNEST F. HOHWART.

10 REFERENCES CITED The following references are of record in the filev of this patent:

5 UNITED STATES PATENTS Number Name Date 152,779 Van Fleet July 7, 1874 1,426,541 Bisset Aug. 22, 1922 10 1,934,411 Dahlman Nov. 7, 1933 1,956,318 Draper Apr. 24, 1934 2,331,111 Dunn Oct. 5, 1943 2,389,366 Jones Nov. 20, 1945 15 FOREIGN PATENTS Number Country Date 10,866 Sweden 1900 443,679 France 1912 474,962 Great Britain 1937 

